This invention relates to a cannister purge valve assembly for a vehicle emission controls valve system.
Existing vehicle emission regulations require that evaporative emissions from the vehicle fuel tank be substantially reduced from current levels. In order to accomplish this reduction in emissions, a cannister is installed on the vehicle and is filled with a desiccant material to absorb vapors which may accumulate in the vehicle fuel tank. However, to minimize the cost of the cannister and the space required for it, a purge valve is necessary. The purge valve normally prevents communication between the fuel tank and the cannister to thereby trap most of the fuel vapors in the fuel tank, but actuates to permit communication between the fuel tank and the cannister when the vapor pressure in the fuel tank rises above a predetermined level. When the vehicle engine is operating, the vapors are purged from the cannister. Other designs for a purge valve of this type have been proposed, but these designs are not able to effectively seal between the various inlets and outlets required on the purge valve housing.